Luffing davit



May 28, 1940. M. c. LE @Eu 2,202,457

LUFFING DAVIT f Filed Sept. 2'7,V 1958 2 Sheets-Sheet 1 M. C; LE GEULUFFING DAvIT Filed Sept. 27, 1938 2 Sheets-Sheet 2 Patented vMay 28,1940 2,202,457 LUFFING nAvI'r Marinus C. Le Geu, Hamburg, Germany,assignor to Ane Pieter Schat, Utrecht,'Netherlan ds ApplicationSeptember 27, 1 938, Serial No. 231,983 In Germany September 30, 1937 1Claim.

This invention relates to a luiling davit of the: type, in which the topend of the davit arm or boom is engaged by an element, such as a screwspindle, by means of which t'he davit arm is w adapted to be positivelyurged inboard and outboard.

My present invention has for its main object an improved davit of thetype referred to, in

which the davit arm is vsubstantially free from bending andtorsionalfstressesl With this object in view, my novel davit comprises aboom, the topI end of which is connected to a lateral brace adapted tobe pivoted to the ships deck.

The invention lwill be further described with reference to theaccompanying'fdrawlings, ing' which like references. indicate similarparts throughout.

Fig. l is a side View of a ships davit in ac-y cordance with theinvention, the full lines indieating the normal inboard position of thedavit, and the dotted lines the outboard position, i. e.

the position in which the boat suspended from the davit is fully swungout.

Fig. 2 is a corresponding front view. Figs. 3-8 are views showing indetail the construction of the upper end of the davit arm, and theforces acting thereon.v Fig. 9 is a side elevational viewfof secondembodiment of the invention.

Referring now particularly to Figures 1 and 2, I denotes the davit armor boom pivoted as at I2 to a stanchion 3 which issecured to the shipsboom I, the other end being rotatably housed in a casing I I, whichitself is pivotally connected as at I2 to the stanchion'3. The screwspindle is adapted to be operated by means of a crank4 handle I3.

A diagonal brace or tie rod I4 is pivoted aty itsupper end to an eye I5of the boom I, and

at its lower end to a bracket 4I6 secured to the deck 4. f l

It will be seen that in any position of the davit, the boom is kept inbalance by three forces, viz., the tensions in therope l, in. the screwspindle 9 and in the brace I4. These three forces are denoted by L, Wand N, respecaxis of said arm. The moment of torsion or.

be raised (Cl. 9-22) Y tively in Figs.- 3-7, whichshow the head of theboom with the parts 8, I 0 and I5 for attaching the boat f5, the screwspindle tand thebrace I4, respectively. 'I heycan be resolved, in thewellknown manner, :intocompo-nents parallel with and at right angles tothe' axis ofthe boom I.

Fig. 4 shows the resolution" of the stress Lv in rope I into itshorizontal-`cornponent H and its vvertical component' V.4 In Fig. 3, thecomponent V is further resolved into the forces P and O.

As will appear from Figs. 3 and 5, the stress in the spindle 9 and thetension N Vin the brace I4 are resolved into the components X, Y, and M,J, respectively, it being understood that the forces P and H aresubstantially `equal to theVv forces X and M, respectively.

Fig. 6. shows the boom head in "transverse section and the forces actingat right angles to the torque acting upon theboom vis;

` T=H.a-P.b

Figs. 7 and 8 showv the forces acting in a vdi rection parallel to theaxis of the davit arm. 'I'he bending moments inthe plane of Vswingingmovement of the boom, andina planeV at right angles thereto are,respectively:

1 B1=O.h- Y.g-J.m and p I B2=O.e|-Y.d-J.`c

According to the invention,the various dimensions a, b, c, d, e, g, handm are preferably so chosen as to render themoments T, B1 andr B2substantially nil, wherebyl the davit arm I is substantially free frombending and torsiona stresses. n Fig. Qshows afurther embodiment oftheinvention. Instead of being pivoted to the davit arm, the bracey I4 isvrigidly secured to the head, and also, by braces I'I, I8, to the.portion inter-` mediate the ends of said arm,

WhatIclaim is: 1

lA luing davit comprising a boom vpivo-tally connected to a ships deck,means for suspend ving a life boat from the topfendof said boom, anelement engaging the'top end of lsaid boom and adapted ywhen operated topositively urge said boom inward or outward, and a lateral braceVconnected'to said boom, said element and said brace being arranged inoffset relation .with the boom in such a manner that'the torsional andbending moments acting upon said boom under theinfluence of a boatsuspended therefrom are substantially nil: l 55 '-MAnIrIrLsC LEVGEU,`

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